Sammi Nelson-Saunders stood in a crowd of blue and purple shirts, dirt on her hands and a smile on her face. Behind her, music was blasting and flowers were being planted as more than 300 volunteers built a new playground for students at KIPP Baltimore.

The rising third-grader at KIPP, a Knowledge is Power Program charter school in Northwest Baltimore, had been used to playing on an empty field adjacent to the school.

"I was very excited because we never had a playground, and now we have a playground to play on," Nelson-Saunders said. "Children need to get exercise and have fun."

The new playground was constructed in one day with help and funding from the CarMax Foundation, the philanthropic branch of used-car retailer CarMax, and KaBOOM, a national nonprofit dedicated to bringing playgrounds to children in locations without designated play areas.

Local volunteers joined helpers from CarMax and KaBOOM last week to erect the newest addition to the charter school. Housed in a former middle school building, KIPP Baltimore had no playground for its 1,200 elementary and middle-school students. Organizers had hoped for about 200 volunteers and were delighted when nearly 300 showed up.

The students "desperately need[ed] a place to play," Hilarie Szczygiel, KIPP's director of recruitment communications, said. While the playground is based on the campus, it will not be closed off, allowing for anyone in the community to use it, said Szczygiel.

The project was started when CarMax and KaBOOM partnered to build 30 playgrounds across the nation. The school was selected after KaBOOM scoured the area to find a site that needed a playground, according to Mike Vietti, senior manager of communications for the nonprofit.

"We are creating a community that will really entice individuals from [the neighborhood] to support KIPP and that playground going forward," Vietti said.

After plans were finalized to bring a playground to the school, students took part in the design process by drawing what they wanted in a dream playground. Organizers compiled the designs and included the most desired features in the new playground, according to Vietti.

Parents were nearly as excited as their children about opening the new playground.

"Already today, I had to hold back tears because I am overjoyed with emotion just watching everyone work together, moving sandboxes, moving benches, hauling mulch. But I thought to myself, 'I better hold it back for the ribbon cutting,' " said Sheryl Flythe, a parent of a fourth-grader at KIPP. Flythe, who also is a member of the parent organization, Team Organize, and the KIPP Baltimore executive board, added: "It's been a glorious day. I'm looking forward to the end result."

The playground is an investment in a city charter school catering mostly students from underserved communities; an estimated 80 percent of graduates go on to college.

KaBOOM was founded in 1996 in Washington, D.C., and has built about 2,200 playgrounds nationally. The organization's $4.1 million partnership with the CarMax Foundation is projected to bring playgrounds to 100,000 children across the country.

"Play is so important. One in five children in this country do not live within walking distance of a place to play," said Leslie Papart, manager of the CarMax Foundation. "The ability to play, physical activity and problem solving and innovation all come together in play, and we know lifelong relationship skills are developed, so we are really working for the future by building these playgrounds."

KaBOOM is looking for places to build playgrounds. The nonprofit encourages any organization in the Baltimore area in need of a playground to apply at kaboom.org.